This invention relates to a filament trimmer having an outwardly extending flexible filament that cuts grass or other ground growing vegetation when the filament is rotated in a cutting plane. More particularly, this invention relates to a filament trimmer having a cutoff blade for cutting the filament to a predetermined length.
Filament trimmers are well known lawn and garden implements. Such a trimmer includes a rotatable trimmer head that has an outwardly extending flexible filament. When the trimmer head is rotated by a drive contained on the trimmer, the filament is spun in a cutting plane to be able to sever grass or other ground growing vegetation. The drive for rotating the trimmer head may be an electrical motor operated by an electrical power source, e.g. a battery on the trimmer or an external electric power cord plugged into the trimmer. The drive may also be a drive shaft operated by an internal combustion engine carried on the trimmer.
Many filament trimmers have a filament feed system for replenishing the filament as the filament becomes shortened due to breakage or wear. Essentially, the feed system feeds out new filament from a supply of filament maintained within the trimmer head with the new filament serving to increase the length the filament extends outwardly from the trimmer head. Because the filament feeding occurs rapidly and also often feeds out filament in discrete increments, it is difficult to precisely control the length of the filament during a replenishment operation. Thus, most filament trimmers employ a cutoff blade that cuts the filament to a desired predetermined length at the conclusion of a filament replenishment operation.
The cutoff blade in prior filament trimmers is fixed in a single location on the trimmer. This provides the filament with a single predetermined length when the filament has just been replenished and is fresh, i.e. prior to the filament having become shortened due to wear or breakage. The Applicants have discovered that there are some circumstances in which it would be desirable to be able to vary the length of a fresh or newly replenished filament. For example, when trimming grass over a large, unobstructed expanse, a relatively long filament is desirable. When trimming in close quarters or near delicate vegetation, a shorter filament might be better. However, prior to this invention, there has not been any way to selectively vary the length of the filament in a filament trimmer.
This invention relates to a filament trimmer having at least one cutoff blade for establishing a predetermined length of a filament when the filament is new prior to the filament being shortened due to breakage or wear. The cutoff blade is adjustably carried on the trimmer to allow the operator to selectively change the predetermined length of the filament when the filament is newly replenished.
One aspect of this invention relates to a filament trimmer that comprises a rotatable trimmer head carried on a housing. The trimmer head includes an outwardly extending filament that cuts grass or other ground growing vegetation when the trimmer head is rotated. The trimmer head includes a filament feed system that replenishes the length of the filament when the filament is shortened due to breakage or wear. A cutoff blade is provided on the trimmer housing such that the filament contacts the cutoff blade as its length increases during replenishment of the filament by the filament feed system. The cutoff blade cuts the filament to a predetermined length at the conclusion of filament replenishment. The cutoff blade is selectively movable by the operator between at least two different positions on the trimmer housing to allow the operator to select a longer or shorter predetermined length for a newly replenished filament.